Length, 14.3; antero-posterior diameter at aperture, 2.25; at largest, 3.33 ; at apex, 1.0; lateral diameter at aperture, 2.3 ; at largest, 3.4; at apex, 1.1 mm. (Pilsbry and Sharp.)

Shell large and solid, well-curved ; smooth and glossy, growth-lines being very faintly indicated ; opaque white, the posterior half bluish, subtranslucent, with a similarly colored rim at the mouth, or sometimes slightly bluish throughout. Stout, decidedly swollen anteriorly, the greatest diameter contained 4,2 to 4,7 times in the length of shell; the equator about at the anterior fourth, either oblique, well-marked and slightly subangular, or less distinct and gently rounded, tapering rapidly toward both ends ; outline of concave side noticeably convex in the region of greatest swelling. Section of tube a trifle flattened between the convex and concave sides at the equator or throughout. Aperture subcircular, somewhat oblique. Anal orifice rather large, slightly oval, with no noticeable callus within; its edge irregular from breakage, but possibly two lateral nicks may be normally present.

Clarence Strait, Alaska, to Manta, Ecuador.

TYPE in United States National Museum, No. 107698.